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Publication numberUS4260350 A
Publication typeGrant
Application numberUS 06/140,648
Publication dateApr 7, 1981
Filing dateApr 16, 1980
Priority dateApr 16, 1980
Publication number06140648, 140648, US 4260350 A, US 4260350A, US-A-4260350, US4260350 A, US4260350A
InventorsLuther O. Russell, Jr.
Original AssigneeFiber Industries, Inc.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Filter for high viscosity liquids
US 4260350 A
Abstract
An improved replaceable filtration unit for high viscosity fluids, of the self sealing semi-disposable type and having inert granular material supported by a screen within a housing, wherein the improvement comprises having the screen's rim swaged into the housing, preferably with an interference fit within the range 0.005 to 0.015 inches. The invention improves the performance of packs used to filter and extrude molten polymer into shaped articles.
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Claims(15)
What I claim is:
1. An improved replaceable pack for filtering pressurized high viscosity molten polymer and extruding the filtered polymer into shaped articles such as filaments and films, which pack comprises a housing having an inlet port and an outlet port, a lid having an inlet port and the lid being rigidly connected via a first gasket to the housing around the housing's inlet port, an extrusion die rigidly connected via a second gasket around the housing's outlet port, an internal lip within the housing between the extrusion die and the inlet port of the housing, means for filtering the fluid immediately upstream of the lip, which filtering means comprises inert granular material immediately upstream of a supporting rimmed fine mesh screen whose annular rim contacts the housing's internal lip, wherein the improvement comprises:
said screen's rim is outwardly swaged and toggle jointed into said housing,
whereby there is a reduced chance of some of said fluid and said granular material by-passing said screen.
2. The pack of claim 1 wherein said swaged rim has an interference fit within the range 0.005 to 0.015 inches.
3. The pack of claim 2 wherein said screen is at least partly annular in shape.
4. The pack of claim 2 which further comprises a grooved bridge plate downstream of said screen and wherein said screen is in the shape of a top hat, and said rim's inner surface is swaged into said bridge plate.
5. The pack of claim 2 wherein said first gasket is a metal sleeve having a length, L, outer diameter, D, and wall thickness T; and said housing's inlet port has a square step around said inlet port's inner face, said step having a radial depth of about T and a height, h, and the value of h is less than L, and the value of L/T is in the range of 2 to 10, whereby the chance of fluid leakage at the lid is reduced.
6. The pack of claim 5 wherein said lid has a counter bore of diameter about D and depth d, and the value of the sum of h and d is less than L in the unassembled state and equal to L in the assembled state.
7. The pack of claim 5, wherein L/T is in the range of 4 to 7.
8. The pack of claim 7, wherein T is in the range of 0.025 to 0.100 inches.
9. The pack of claim 8, wherein said metal sleeve comprises aluminum, copper, mild steel or stainless steel.
10. The pack of claim 2 wherein said housing has a second lip around said housing's exit port, and said extrusion die is rigidly connected to said second lip via a second gasket by pressure of said pressurized fluid.
11. An improved replaceable filtration unit for high viscosity fluids, which filter unit comprises a housing having an inlet port and an exit port, a rimmed fine mesh screen between the ports for filtering the fluid, wherein the improvement comprises:
said screen's rim is swaged into said housing.
12. The pack of claim 1 wherein said screen's rim has an uncorrugated shape prior to being swaged.
13. The pack of claim 1 wherein said screen's rim is changed from a frustoconical shape to a planar shape during swaging.
14. The pack of claim 12 wherein said swaged rim has an interference fit within the range 0.005 to 0.015 inches.
15. The pack of claim 13 wherein said swaged rim has an interference fit within the range 0.005 to 0.015 inches.
Description

This is a continuation of application Ser. No. 920,611, filed June 29, 1978, now abandoned.

BACKGROUND OF THE INVENTION

(i) Field of the Invention

The invention relates broadly to the filtration of fluids. More particularly, it relates to seals in replaceable packs for filtering highly pressurized high viscosity molten polymer and extruding the filtered polymer into shaped articles such as filaments and films.

(ii) Prior Art

Packs for filtering pressurized high viscosity polymeric material and forming the filtered liquid into spun filaments are well known in the art. A pack of relatively recent design and its mode of operation is disclosed in U.S. Pat. No. 3,307,216. Typically, all such packs are assembled from a mixture of re-useable components (such as housing, lid, spinnerette) and disposable components (such as inert granular material, gaskets, and screens for supporting the inert granular material). The average time interval between replacing packs has a significant effect on both the economics of the process and the quality of the product.

SUMMARY OF THE INVENTION

The invention arose out of the discovery that the type of pack disclosed in the forementioned U.S. Pat. No. 3,307,216 had certain drawbacks, particularly for the spinning of highly viscous material at high throughputs. In particular, it was found that some of the seals for controlling polymer flow were not consistently effective, resulting in both external polymer leaks out of the pack, and internal polymer leaks (or by-passing) within the pack. Both types of leak are highly undesirable.

It has now been found that the claimed invention, in which the rim of the screen supporting the inert granular material is swaged into the housing, significantly reduces the number of these highly undesirable leaks, and in addition halves the time to assembly the pack components into an integral unit. The improved seal design may be used with advantage in any replaceable filter of the type described regardless of whether the filter is integrally combined with an extrusion die. The improved seal designs are extremely valuable in melt spinning packs designed for use in combination with already constructed apparatus that imposes severe space limitations. The invention is surprising, particularly since the type of seal shown in U.S. Pat. No. 3,307,216 has been used commercially for over ten years in the manufacture of many billions of pounds of fiber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross section of an assembled melt spinning pack of the invention.

FIGS. 2, 3 AND 4 are horizontal fragmentary cross sections along lines 2--2, 3--3 and 4--4 respectively of FIG. 1.

FIG. 5 is a perspective view of an unassembled "top hat" screen and corresponds to item 6 of FIG. 1 in assembled form.

FIG. 6 is an enlarged view of Zone A of FIG. 1, as it looks during assembly of the pack prior to the swaging operation.

FIG. 7 is an enlarged view of Zone B of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Figures illustrate the preferred embodiments of the invention.

FIG. 1 is a vertical cross section of an assembled melt spinning pack incorporating the invention. In particular, FIG. 1 shows an improved replaceable pack for filtering pressurized high viscosity molten polymer and extruding the filtered polymer into shaped articles such as filaments and films, which pack comprises a housing (9) having an inlet port (19) and an outlet port (20), a lid (15) having an inlet port (11) and an exit port (21) and the lid being rigidly connected via a first gasket (7) to the housing around the lid's exit port and around the housing's inlet port, an extrusion die (2) rigidly connected via a second gasket (3) around the housing's outlet port, an internal lip (5) within the housing between the extrusion die and the inlet port of the housing, means for filtering the fluid immediately upstream of the lip, which filtering means comprises inert granular material (16) immediately upstream of a supporting rimmed fine mesh screen (6) whose annular rim contacts the housing's internal lip (5), wherein the improvement comprises: said screen's rim is swaged into said housing, whereby there is a reduced chance of some of said fluid and said granular material by-passing said screen. Likewise, FIG. 1 also illustrates an improved replaceable filtration unit for high viscosity fluids, which filter unit comprises a housing (9) having an inlet port (19) and an exit port (20), a rimmed fine mesh screen (6) between the ports for filtering the fluid, wherein the improvement comprises: said screen's rim is swaged into said housing.

FIG. 6 is an enlargement of Zone "A" prior to swaging of the rim of screen (6) into both the housing (9) and a grooved bridge plate (5). The screen is in the shape of a top hat and at least partly annular. It is preferred that the total radial interference fit imposed upon the rim of the screen be between 0.005 and 0.015 inches. Thus, in FIG. 6, the dimension A2 is greater than dimension A1, by an amount within the range of about 0.005 to 0.015 inches. Also, the dimension B2 is preferably greater than the dimension B1 by an amount up to 0.002 inches. It will, of course, be appreciated by one skilled in the art, that swaging of the unswaged rim of the screen as shown in FIG. 6 (and having the relative dimensions of A, A2, B1 and B2 as defined above) into the swaged rim as shown in FIG. 1, Zone A, must inherently result in the rim being outwardly swaged and toggle jointed into the housing. Webster's New Collegiate Dictionary (1961) defines toggle joint as "(a) device consisting of two bars jointed together end to end but not in line, so that when a force is applied to the knee tending to straighten the arrangement, the parts abutting . . . the ends of the bars will experience an endways pressure."

FIG. 7 is an enlargement of Zone B of FIG. 1, and shows the seal between the pack housing and lid. It shows a first gasket (7) in the form of a metal sleeve having a length, L, outer diameter, D, and wall thickness, T; and the housing's inlet port (19) has a square step around its inner face. The square step has a radial depth of about T and a height h. The value of h must be less than the value of L. It is preferred that the value of L/T be in the range 2 to 10, and most preferably in the range 4 to 7. It is preferred that T be in the range from 0.025 to 0.100 inches. The metal sleeve is preferably aluminum, copper, mild steel or stainless steel. It is preferred that the inside face of the lid has a counter bore of diameter D and depth d, and the value of the sum of h and d is equal to L in the assembled state and less than L in the unassembled state.

It is preferred that the third and remaining seal with the pack, the seal between the extrusion die (2) and the housing's outlet port (20) be obtained conventionally as shown in FIG. 1, which shows the housing (9) having a second lip around its exit port (20) that is rigidly connected to the extrusion die via a second gasket (3) by means of the pressure of the pressurized fluid within the pack.

while the foregoing, in combination with the drawings, illustrates the broadest and most preferred embodiments of the invention, it will of course be appreciated that other embodiments of the invention come within the scope of the broadest claims.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2038348 *Jan 28, 1935Apr 21, 1936Lyonnaise De Textiles SocIndividual filter for the spinning of artificial filaments, threads, and the like
US2266368 *Nov 10, 1938Dec 16, 1941Du PontApparatus for the production of artificial structures
US2607954 *Jun 17, 1950Aug 26, 1952Celanese CorpMethod and apparatus for forming gel-free thermoplastic films
US2732585 *Feb 12, 1952Jan 31, 1956 Spinner head
US3307216 *Oct 5, 1964Mar 7, 1967Fiber Industries IncAnnular spinning apparatus
US3469279 *Oct 15, 1964Sep 30, 1969British Nylon Spinners LtdSpinneret for heterofilaments
US3475527 *Dec 11, 1967Oct 28, 1969Monsanto CoProcess for destroying melt crystalline order in fiber-forming polymers
US3724064 *May 3, 1972Apr 3, 1973Mott Metallurg CorpSealing method
US3771664 *Jul 5, 1972Nov 13, 1973Dover CorpFilter seal
US3797982 *May 8, 1972Mar 19, 1974Colgate Palmolive CoExtruder output multiplier
JPS538811A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5217659 *Dec 17, 1991Jun 8, 1993Wellman, Inc.Repair of filtration elements for polymer manufacture
US5246589 *Jan 12, 1993Sep 21, 1993Wellman, Inc.Repaired filtration elements for polymer manufacture
US5387097 *Dec 7, 1992Feb 7, 1995Akzo NvSelf-sealing spin pack
US6171536 *Apr 10, 1998Jan 9, 2001Arteva North America S.A.R.L.Apparatus and method for melt spinning of molten polymeric material
US7520137 *Jun 2, 2005Apr 21, 2009Alstom Technology LtdMethod of controlling the injection of liquid into an inflow duct of a prime mover or driven machine
Classifications
U.S. Classification425/197, 425/198, 264/176.1
International ClassificationB01D29/00, D01D1/10
Cooperative ClassificationB01D29/0036, D01D1/106, B01D29/0027
European ClassificationB01D29/00A8, D01D1/10D, B01D29/00A10K14
Legal Events
DateCodeEventDescription
Mar 19, 1984ASAssignment
Owner name: CELANESE CORPORATION A DE CORP
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:FIBER INDUSTRIES INC;REEL/FRAME:004239/0763
Effective date: 19841230